Being good at aikido as a beginner doesn't mean you will be in that state forever. You will go through different stages when you advance and most likely you will also struggle. You will also experience plateaus and heartaches. Aikido is not about learning techniques per se or just good body coordination, it is something much greater. Techniques are only tools to give you an insight to what aikido really is.
It is difficult to rate a teacher. It's catch 22 actually. You will know a good teacher if you know good aikido. IMHO you will only know good aikido probably at shodan level where you are a serious beginner. For me, if I don't have this, lineage is somewhat important. Teachers do make a significant difference. You might want to look at this. Has he trained with credible teachers? What about your most senior students, how much have they progressed?
Just from your description though, it looks like your teacher is doing the right things but I havnt seen your teacher's aikido so I really can't judge.
Focussing on the basics
Emphasis on the details.
Going slow. If you can perform techniques very slowly, you can perform them fast. It doesn't work the other way around.
Let me test your aikido then
,5% of the teaching comes from the teacher and 95% comes from you. If you are able to understand this, then there will be no dead-end for you.